Interventions that reach the majority of cigarette smokers in the population have the greatest potential to impact the public health. Most smokers do not seek treatment for smoking cessation. A novel behavioral approach to reaching smokers is to directly recruit and train adult nonsmokers to intervene (i.e., support persons). Several studies provide evidence for the role of social support in smoking cessation. The use of support persons as change agents for smoking cessation represents a shift from conventional interventions that focus almost exclusively on the smoker. This proposal builds on our previous work that indicates a skills training intervention for support persons is feasible and acceptable to participants. Moreover, the effect size observed for the smoking abstinence rate in the smokers, as reported by the support persons, provides some evidence of potential efficacy. However, the intensive, group, clinic-based format of the intervention limits its potential dissemination. We propose to develop and pilot test a more streamlined version of the intervention using a telephone-based format. To enhance internal validity of the findings, additional formative work is also needed to examine the feasibility of obtaining baseline assessments and outcomes directly from the smoker. Social cognitive theory is the conceptual basis for the proposed intervention. The objective of this R21 proposal is to develop and pilot test a novel behavioral approach to smoking cessation that utilizes support persons in the smoker's natural environment. We expect that as a result of this project, we will have developed a well-specified and feasible telephone counseling intervention, the efficacy of which can be tested in future larger-scale randomized clinical trials. This project will take place in two phases. In Phase 1, we will develop a telephone counseling intervention for support persons, adapting and refining the intervention from our previous, clinic-based treatment study. During this phase, we will develop the telephone counselor manual, and 10 support persons will complete the protocol, which will be modified and refined based on feedback from participants and counselors. Phase 2, consisting of a pilot clinical trial, will apply a randomized, two group design with repeated assessments at weeks 0 (baseline), 10 (end-of-treatment), and 26. Support persons (N=60) will be recruited and randomly assigned to self-help intervention or telephone counseling. The smokers will be enrolled as study subjects but will be contacted for assessments only.